Mordenite, when it is produced according to known processes has a predominant amount of particles in the size range of 6 to 12 .mu.m. Therefore for its use as catalyst this powder must be formed into larger particles either in its production or subsequently (compare German Pat. No. 1,176,106 and German AS No. 2,055,476). Furthermore, it is known from Rollmann U.S. Pat. No. 4,205,052 to influence the crystal form of the mordenite during the crystallization by addition of organic compounds. The entire disclosure of Rollmann is hereby incorporated by reference and relied upon.
This known process has the disadvantage that it either requires further process steps or expensive materials.